The Liquid Crystal Display (LCD) possesses advantages of thin body, power saving and no radiation to be widely used in many application scope, such as LCD TV, mobile phone, personal digital assistant (PDA), digital camera, notebook, laptop, and dominates the flat panel display field.
Most of the liquid crystal displays on the present market are backlight type liquid crystal displays, which comprise a liquid crystal display panel and a backlight module. The working principle of the liquid crystal display panel is that the Liquid Crystal is injected between the Thin Film Transistor Array Substrate (TFT array substrate) and the Color Filter (CF). The light of backlight module is refracted to generate images by applying driving voltages to the two substrates for controlling the rotations of the liquid crystal molecules.
In the active liquid crystal display, each pixel is electrically coupled to a thin film transistor (TFT), and the gate thereof is coupled to a level scan line, and the drain is coupled to a vertical data line, and the source is coupled to the pixel electrode. The enough voltage is applied to the level scan line, and all the TFTs electrically coupled to the horizontal scan line are activated. Thus, the signal voltage on the data line can be written into the pixel to control the transmittances of different liquid crystals to achieve the effect of controlling colors and brightness. The driving of the level scan line in the present active liquid crystal display is mainly accomplished by the external Integrated Circuit (IC). The external IC can control the charge and discharge stage by stage of the level scan lines of respective stages. The GOA technology, i.e. the Gate Driver on Array technology can utilize the original manufacture processes of the liquid crystal display panel to manufacture the driving circuit of the level scan lines on the substrate around the active area, to replace the external IC for accomplishing the driving of the level scan lines. The GOA technology can reduce the bonding procedure of the external IC and has potential to raise the productivity and lower the production cost. Meanwhile, it can make the liquid crystal display panel more suitable to the narrow frame or non frame design of display products.
Generally, the GOA circuits may have the GOA circuit based on P-type thin film transistor, the GOA circuit based on CMOS and the GOA circuit based on N-type thin film transistor. The GOA circuit based on P-type thin film transistor, and particularly the GOA circuit based on P-type thin film transistor which the Low Temperature Poly-silicon (LTPS) is the material has properties of simpler art, low electrical leakage, and the development prospect is great. However, the GOA circuit based on P-type thin film transistor according to prior art often has worse stability and the power consumption is higher.